/**
 *    Copyright ${license.git.copyrightYears} the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.mybatis.generator.api;

import static org.mybatis.generator.internal.util.ClassloaderUtility.getCustomClassloader;
import static org.mybatis.generator.internal.util.messages.Messages.getString;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.mybatis.generator.codegen.RootClassInfo;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.Context;
import org.mybatis.generator.config.MergeConstants;
import org.mybatis.generator.exception.InvalidConfigurationException;
import org.mybatis.generator.exception.ShellException;
import org.mybatis.generator.internal.DefaultShellCallback;
import org.mybatis.generator.internal.ObjectFactory;
import org.mybatis.generator.internal.NullProgressCallback;
import org.mybatis.generator.internal.XmlFileMergerJaxp;

/**
 * This class is the main interface to MyBatis generator. A typical execution of the tool involves these steps:
 * 
 * <ol>
 * <li>Create a Configuration object. The Configuration can be the result of a parsing the XML configuration file, or it
 * can be created solely in Java.</li>
 * <li>Create a MyBatisGenerator object</li>
 * <li>Call one of the generate() methods</li>
 * </ol>
 *
 * @author Jeff Butler
 * @see org.mybatis.generator.config.xml.ConfigurationParser
 */
public class MyBatisGenerator {

  /** The configuration. */
  private Configuration configuration;

  /** The shell callback. */
  private ShellCallback shellCallback;

  /** The generated java files. */
  private List<GeneratedJavaFile> generatedJavaFiles;

  /** The generated xml files. */
  private List<GeneratedXmlFile> generatedXmlFiles;

  /** The warnings. */
  private List<String> warnings;

  /** The projects. */
  private Set<String> projects;

  /**
   * Constructs a MyBatisGenerator object.
   * 
   * @param configuration
   *          The configuration for this invocation
   * @param shellCallback
   *          an instance of a ShellCallback interface. You may specify <code>null</code> in which case the
   *          DefaultShellCallback will be used.
   * @param warnings
   *          Any warnings generated during execution will be added to this list. Warnings do not affect the running of
   *          the tool, but they may affect the results. A typical warning is an unsupported data type. In that case,
   *          the column will be ignored and generation will continue. You may specify <code>null</code> if you do not
   *          want warnings returned.
   * @throws InvalidConfigurationException
   *           if the specified configuration is invalid
   */
  public MyBatisGenerator(Configuration configuration, ShellCallback shellCallback, List<String> warnings)
      throws InvalidConfigurationException {
    super();
    if (configuration == null) {
      throw new IllegalArgumentException(getString("RuntimeError.2")); //$NON-NLS-1$
    } else {
      this.configuration = configuration;
    }

    if (shellCallback == null) {
      this.shellCallback = new DefaultShellCallback(false);
    } else {
      this.shellCallback = shellCallback;
    }

    if (warnings == null) {
      this.warnings = new ArrayList<String>();
    } else {
      this.warnings = warnings;
    }
    generatedJavaFiles = new ArrayList<GeneratedJavaFile>();
    generatedXmlFiles = new ArrayList<GeneratedXmlFile>();
    projects = new HashSet<String>();

    this.configuration.validate();
  }

  /**
   * This is the main method for generating code. This method is long running, but progress can be provided and the
   * method can be canceled through the ProgressCallback interface. This version of the method runs all configured
   * contexts.
   *
   * @param callback
   *          an instance of the ProgressCallback interface, or <code>null</code> if you do not require progress
   *          information
   * @throws SQLException
   *           the SQL exception
   * @throws IOException
   *           Signals that an I/O exception has occurred.
   * @throws InterruptedException
   *           if the method is canceled through the ProgressCallback
   */
  public void generate(ProgressCallback callback) throws SQLException, IOException, InterruptedException {
    generate(callback, null, null, true);
  }

  /**
   * This is the main method for generating code. This method is long running, but progress can be provided and the
   * method can be canceled through the ProgressCallback interface.
   *
   * @param callback
   *          an instance of the ProgressCallback interface, or <code>null</code> if you do not require progress
   *          information
   * @param contextIds
   *          a set of Strings containing context ids to run. Only the contexts with an id specified in this list will
   *          be run. If the list is null or empty, than all contexts are run.
   * @throws SQLException
   *           the SQL exception
   * @throws IOException
   *           Signals that an I/O exception has occurred.
   * @throws InterruptedException
   *           if the method is canceled through the ProgressCallback
   */
  public void generate(ProgressCallback callback, Set<String> contextIds) throws SQLException, IOException,
      InterruptedException {
    generate(callback, contextIds, null, true);
  }

  /**
   * This is the main method for generating code. This method is long running, but progress can be provided and the
   * method can be cancelled through the ProgressCallback interface.
   *
   * @param callback
   *          an instance of the ProgressCallback interface, or <code>null</code> if you do not require progress
   *          information
   * @param contextIds
   *          a set of Strings containing context ids to run. Only the contexts with an id specified in this list will
   *          be run. If the list is null or empty, than all contexts are run.
   * @param fullyQualifiedTableNames
   *          a set of table names to generate. The elements of the set must be Strings that exactly match what's
   *          specified in the configuration. For example, if table name = "foo" and schema = "bar", then the fully
   *          qualified table name is "foo.bar". If the Set is null or empty, then all tables in the configuration will
   *          be used for code generation.
   * @throws SQLException
   *           the SQL exception
   * @throws IOException
   *           Signals that an I/O exception has occurred.
   * @throws InterruptedException
   *           if the method is canceled through the ProgressCallback
   */
  public void generate(ProgressCallback callback, Set<String> contextIds, Set<String> fullyQualifiedTableNames)
      throws SQLException, IOException, InterruptedException {
    generate(callback, contextIds, fullyQualifiedTableNames, true);
  }

  /**
   * This is the main method for generating code. This method is long running, but progress can be provided and the
   * method can be cancelled through the ProgressCallback interface.
   *
   * @param callback
   *          an instance of the ProgressCallback interface, or <code>null</code> if you do not require progress
   *          information
   * @param contextIds
   *          a set of Strings containing context ids to run. Only the contexts with an id specified in this list will
   *          be run. If the list is null or empty, than all contexts are run.
   * @param fullyQualifiedTableNames
   *          a set of table names to generate. The elements of the set must be Strings that exactly match what's
   *          specified in the configuration. For example, if table name = "foo" and schema = "bar", then the fully
   *          qualified table name is "foo.bar". If the Set is null or empty, then all tables in the configuration will
   *          be used for code generation.
   * @param writeFiles
   *          if true, then the generated files will be written to disk. If false, then the generator runs but nothing
   *          is written
   * @throws SQLException
   *           the SQL exception
   * @throws IOException
   *           Signals that an I/O exception has occurred.
   * @throws InterruptedException
   *           if the method is canceled through the ProgressCallback
   */
  public void generate(ProgressCallback callback, Set<String> contextIds, Set<String> fullyQualifiedTableNames,
      boolean writeFiles) throws SQLException, IOException, InterruptedException {

    if (callback == null) {
      callback = new NullProgressCallback();
    }

    generatedJavaFiles.clear();
    generatedXmlFiles.clear();
    ObjectFactory.reset();
    RootClassInfo.reset();

    // calculate the contexts to run
    List<Context> contextsToRun;
    if (contextIds == null || contextIds.size() == 0) {
      contextsToRun = configuration.getContexts();
    } else {
      contextsToRun = new ArrayList<Context>();
      for (Context context : configuration.getContexts()) {
        if (contextIds.contains(context.getId())) {
          contextsToRun.add(context);
        }
      }
    }

    // setup custom classloader if required
    if (configuration.getClassPathEntries().size() > 0) {
      ClassLoader classLoader = getCustomClassloader(configuration.getClassPathEntries());
      ObjectFactory.addExternalClassLoader(classLoader);
    }

    // now run the introspections...
    int totalSteps = 0;
    for (Context context : contextsToRun) {
      totalSteps += context.getIntrospectionSteps();
    }
    callback.introspectionStarted(totalSteps);

    for (Context context : contextsToRun) {
      context.introspectTables(callback, warnings, fullyQualifiedTableNames);
    }

    // now run the generates
    totalSteps = 0;
    for (Context context : contextsToRun) {
      totalSteps += context.getGenerationSteps();
    }
    callback.generationStarted(totalSteps);

    for (Context context : contextsToRun) {
      context.generateFiles(callback, generatedJavaFiles, generatedXmlFiles, warnings);
    }

    // now save the files
    if (writeFiles) {
      callback.saveStarted(generatedXmlFiles.size() + generatedJavaFiles.size());

      for (GeneratedXmlFile gxf : generatedXmlFiles) {
        projects.add(gxf.getTargetProject());
        writeGeneratedXmlFile(gxf, callback);
      }

      for (GeneratedJavaFile gjf : generatedJavaFiles) {
        projects.add(gjf.getTargetProject());
        writeGeneratedJavaFile(gjf, callback);
      }

      for (String project : projects) {
        shellCallback.refreshProject(project);
      }
    }

    callback.done();
  }

  private void writeGeneratedJavaFile(GeneratedJavaFile gjf, ProgressCallback callback) throws InterruptedException,
      IOException {
    File targetFile;
    String source;
    try {
      File directory = shellCallback.getDirectory(gjf.getTargetProject(), gjf.getTargetPackage());
      targetFile = new File(directory, gjf.getFileName());
      if (targetFile.exists()) {
        if (shellCallback.isMergeSupported()) {
          source = shellCallback.mergeJavaFile(gjf.getFormattedContent(), targetFile.getAbsolutePath(),
              MergeConstants.OLD_ELEMENT_TAGS, gjf.getFileEncoding());
        } else if (shellCallback.isOverwriteEnabled()) {
          source = gjf.getFormattedContent();
          warnings.add(getString("Warning.11", //$NON-NLS-1$
              targetFile.getAbsolutePath()));
        } else {
          source = gjf.getFormattedContent();
          targetFile = getUniqueFileName(directory, gjf.getFileName());
          warnings.add(getString("Warning.2", targetFile.getAbsolutePath())); //$NON-NLS-1$
        }
      } else {
        source = gjf.getFormattedContent();
      }

      callback.checkCancel();
      callback.startTask(getString("Progress.15", targetFile.getName())); //$NON-NLS-1$
      writeFile(targetFile, source, gjf.getFileEncoding());
    } catch (ShellException e) {
      warnings.add(e.getMessage());
    }
  }

  private void writeGeneratedXmlFile(GeneratedXmlFile gxf, ProgressCallback callback) throws InterruptedException,
      IOException {
    File targetFile;
    String source;
    try {
      File directory = shellCallback.getDirectory(gxf.getTargetProject(), gxf.getTargetPackage());
      targetFile = new File(directory, gxf.getFileName());
      if (targetFile.exists()) {
        if (gxf.isMergeable()) {
          source = XmlFileMergerJaxp.getMergedSource(gxf, targetFile);
        } else if (shellCallback.isOverwriteEnabled()) {
          source = gxf.getFormattedContent();
          warnings.add(getString("Warning.11", //$NON-NLS-1$
              targetFile.getAbsolutePath()));
        } else {
          source = gxf.getFormattedContent();
          targetFile = getUniqueFileName(directory, gxf.getFileName());
          warnings.add(getString("Warning.2", targetFile.getAbsolutePath())); //$NON-NLS-1$
        }
      } else {
        source = gxf.getFormattedContent();
      }

      callback.checkCancel();
      callback.startTask(getString("Progress.15", targetFile.getName())); //$NON-NLS-1$
      writeFile(targetFile, source, "UTF-8"); //$NON-NLS-1$
    } catch (ShellException e) {
      warnings.add(e.getMessage());
    }
  }

  /**
   * Writes, or overwrites, the contents of the specified file.
   *
   * @param file
   *          the file
   * @param content
   *          the content
   * @param fileEncoding
   *          the file encoding
   * @throws IOException
   *           Signals that an I/O exception has occurred.
   */
  private void writeFile(File file, String content, String fileEncoding) throws IOException {
    FileOutputStream fos = new FileOutputStream(file, false);
    OutputStreamWriter osw;
    if (fileEncoding == null) {
      osw = new OutputStreamWriter(fos);
    } else {
      osw = new OutputStreamWriter(fos, fileEncoding);
    }

    BufferedWriter bw = new BufferedWriter(osw);
    bw.write(content);
    bw.close();
  }

  /**
   * Gets the unique file name.
   *
   * @param directory
   *          the directory
   * @param fileName
   *          the file name
   * @return the unique file name
   */
  private File getUniqueFileName(File directory, String fileName) {
    File answer = null;

    // try up to 1000 times to generate a unique file name
    StringBuilder sb = new StringBuilder();
    for (int i = 1; i < 1000; i++) {
      sb.setLength(0);
      sb.append(fileName);
      sb.append('.');
      sb.append(i);

      File testFile = new File(directory, sb.toString());
      if (!testFile.exists()) {
        answer = testFile;
        break;
      }
    }

    if (answer == null) {
      throw new RuntimeException(getString("RuntimeError.3", directory.getAbsolutePath())); //$NON-NLS-1$
    }

    return answer;
  }

  /**
   * Returns the list of generated Java files after a call to one of the generate methods. This is useful if you prefer
   * to process the generated files yourself and do not want the generator to write them to disk.
   * 
   * @return the list of generated Java files
   */
  public List<GeneratedJavaFile> getGeneratedJavaFiles() {
    return generatedJavaFiles;
  }

  /**
   * Returns the list of generated XML files after a call to one of the generate methods. This is useful if you prefer
   * to process the generated files yourself and do not want the generator to write them to disk.
   * 
   * @return the list of generated XML files
   */
  public List<GeneratedXmlFile> getGeneratedXmlFiles() {
    return generatedXmlFiles;
  }
}
